Technique for configuring network interface circuit in integrated services digital network keyphone system

ABSTRACT

A technique for configuring a network interface circuit capable of being commonly used in all countries or networks which have different ISDN protocols, with only one BRI trunk includes the steps of: first storing beforehand in a read only memory (ROM) of the network interface circuit all function programs for supporting an integrated services digital network protocol for each country and network which will be used by the keyphone system, selecting a function program from among the function programs stored in the ROM corresponding the country and kind of network to be operated upon initialization, and setting the selected program, as the function program to be executed.

CLAIM OF PRIORITY

[0001] This application makes reference to, incorporates the sameherein, and claims all benefits accruing under 35 U.S.C. §119 from anapplication for METHOD FOR CONFIGURING NETWORK INTERFACE CIRCUIT ININTEGRATED SERVICES DIGITAL NETWORK KEYPHONE SYSTEM earlier filed in theKorean Industrial Property Office on the Feb. 28, 1997 and there dulyassigned Serial No. 6551/1997.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a keyphone system and, inparticular, to a technique for configuring a network interface circuitfor interfacing an analog keyphone system to an integrated servicesdigital network (hereinafter, referred to as an “ISDN”).

[0004] 2. Description of the Related Art

[0005] While a typical keyphone system has been used by being interfacedwith a public switched telephone network (hereinafter, referred to as aPSTN), it has also been recently used with an ISDN. Herein, the keyphonesystem being interfaced with the ISDN is conventionally called an ISDNkeyphone system. The ISDN keyphone system includes a basic rateinterface (hereinafter, referred to as a “BRI”) of the ISDN and anetwork interface circuit. Therefore, the network interface circuit isgenerally considered as the BRI trunk.

[0006] The BRI trunk used as a device for interfacing the analogkeyphone system with the BRI, performs the ISDN protocol. Also, the BRIis used as an S/T interface of the basic rate interface regulated in theISDN, that is, an interface line between the ISDN and a terminal,including 2B+D channels comprised of two B channels and one D channel.The B channel is used for transmission of voice and data informationwith the transmission rate of 64 Kbps and the D channels are used fortransmission of a control signal with the transmission rate of 16 Kbps.In this BRI trunk, a function program for supporting the ISDN protocolis installed within a read only memory (hereinafter, referred to as aROM) located in the BRI trunk.

[0007] Meanwhile, the ISDN protocol depends upon the country or networkin most cases. Therefore, when different countries or the networksoperate with the ISDN keyphone system, the function program forperforming the ISDN protocol by the BRI trunk of the corresponding ISDNkeyphone system has to be varied accordingly, too. Consequently, it isnecessary for the ROM included in the BRI trunk to contain the functionprogram in conformity with the corresponding country or network.

[0008] As stated hereinafter, since the function program for performingthe ISDN protocol for a specific country or a specific network isincluded in the ROM of the BRI trunk, there is a problem in that the ROMincluded in the BRI trunk must be replaced with a new ROM in conformitywith the corresponding country or network whenever the country ornetwork used by the keyphone system is changed.

[0009] The following patents each disclose features in common with thepresent invention but do not teach or suggest the specifically recitedtechnique for configuring a network interface circuit in an integratedservices digital network keyphone system of the present invention: U.S.Pat. No. 5,666,349 to Petri entitled Method For Controlling ComponentsOf A Communication System, U.S. Pat. No. 5,442,630 to Gagliardi et al.,entitled ISDN Interfacing Of Local Area Networks, U.S. Pat. No.5,574,861 to Lorvig et al., entitled Dynamic Allocation Of B-Channels InISDN, U.S. Pat. No. 5,481,598 to Bergler et al., entitled SubscriberTerminal For ISDN Network, U.S. Pat. No. 5,070,524 to Mano, entitledTelephone System, U.S. Pat. No. 5,617,630 to Feinberg et al., entitledInterface For A Data Telephone And Data Terminal In A Digital TelephoneSystem, U.S. Pat. No. 5,655,001 to Cline et al, entitled WirelessTelecommunication System Using Protocol Conversion For Signaling BetweenBase Stations And Land Based Switches, U.S. Pat. No. 5,062,108 to Baleset al., entitled ISDN Codeset Conversion, U.S. Pat. No. 5,239,542 toBreidenstein et al, entitled Time Division Multiplex Switching SystemFor Interconnecting Telephone Circuits Which Operate In Accordance WithDifferent Signaling Systems And Call Formats, U.S. Pat. No. 5,278,972 toBaker et al., entitled Communication System For Converting ISDNSignaling Protocol Between Local And Public Network Having First GroupOf Mandatory Elements And Second Group Of Non-Mandatory Elements, U.S.Pat. No.5,412,660 to Chen et al., entitled ISDN-To ISDN CommunicationVia Satellite Microwave Radio Frequency Communications Link, and U.S.Pat. No. 5,652,782 to Hughes-Hartogs, entitled Digital TelephoneOvercoming International Incompatibilities.

SUMMARY OF THE INVENTION

[0010] It is an object of the present invention to provide a techniquefor configuring a network interface circuit capable of being commonlyused in all countries or networks which have different ISDN protocols,with only one BRI trunk.

[0011] In order to achieve the above object, the present inventioncomprises a technique for configuring a network interface circuit in anintegrated services digital network keyphone system, comprising thesteps of: first storing beforehand in a read only memory(ROM) of thenetwork interface circuit all function programs for supporting anintegrated services digital network protocol for a country and a networkwhich will be used by the keyphone system, selecting a function programfrom among the function programs stored in the ROM corresponding to thecountry and kind of network to be operated upon initialization, andsetting the selected program, as the function program to be executed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete appreciation of this invention, and many of theattendant advantages thereof, will be readily apparent as the samebecomes better understood by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings, in which like reference symbols indicate the same or similarcomponents, wherein:

[0013]FIG. 1 is a block diagram showing the construction of a BRI trunkof an ISDN keyphone system;

[0014]FIG. 2 is a block diagram showing the construction of software forperforming an ISDN protocol in the BRI trunk of an ISDN keyphone system;

[0015]FIG. 3 is a diagram showing processes of transceiving theconfiguration message between software modules according to anembodiment of the present invention;

[0016]FIGS. 4A and 4B are flowcharts showing processes for processing alayer management entity according to an embodiment of the presentinvention;

[0017]FIGS. 5A and 5B are flowcharts showing processes for processing anapplication entity according to an embodiment of the present invention;

[0018]FIG. 6 is a flowchart showing processes for processing a callcontrol entity according to an embodiment of the present invention;

[0019]FIG. 7 is a flowchart showing processes for processing a networksignaling entity according to an embodiment of the present invention;

[0020]FIG. 8 is a flowchart showing processes for processing a data linkentity according to an embodiment of the present invention;

[0021]FIG. 9 is a flowchart showing processes for processing a physicalentity according to an embodiment of the present invention; and

[0022]FIG. 10 is a flowchart showing processes for processing a maindevice of a keyphone system according to an embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0023] Hereinafter, a preferred embodiment of the present invention willbe concretely explained with reference with accompanying drawings. Mostof all, throughout the drawings, it is noted that the same referencenumerals or letters will be used to designate like or equivalentelements having the same function. Further, in the followingdescription, numerous specific details such as concrete componentscomposing the circuitry and the frequencies, are set forth to provide amore thorough understanding of the present invention. It will beapparent, however, to one skilled in the art that the present inventionmay be practiced without these specific details. A detailed descriptionof known functions and constructions unnecessarily obscuring the subjectmatter of the present invention has been omitted in the followingdescription.

[0024]FIG. 1 is a block diagram showing the construction of a BRI trunk100 of an ISDN keyphone system, where the BRI trunk 100 is connectedbetween a main device 102 of the ISDN keyphone system and 4 lines BRI ofthe ISDN. The BRI trunk 100 includes a CPU (central processing unit)104, a ROM 106, a random access memory (hereinafter, referred to as RAM108, a dual port RAM 110, an IDEC (ISDN D-channel exchange controller)112, an EPIC (extended PCM interface controller) 114, and a QUAT-S(quadruple transceiver for user/network interface-S) 116, which isconnected to the main device 102 of the keyphone system. Therein, themain device 102 generally provides the overall function having theexchange service for central office and extension calls in the ISDNkeyphone system. The CPU 104, the ROM 106, the RAM 108, the dual portRAM 110, and the IDEC 12 are connected with one another via a CPU bus118, and the IDEC 112, the EPIC 114, and the QUAT-S 116 are connectedwith one another via an IOM2 (ISDN-oriented modular 2) interface 120.The CPU bus 118 is comprised of an address bus, a data bus, and acontrol bus. The IOM2 interface 120 used as a 4 wire serial interface isconstructed with two clock lines for synchronization and two data lines.The data lines are composed of two B channels B1 and B2, a D channel, amonitor channel of 64 Kbps, a command/indication channel of 32 Kbps, andMR and MX channels of 8 Kbps for controlling the monitor channel, foreach BRI.

[0025] The CPU 104 performs an operation depending upon the programstored in the ROM 106. The CPU 104 communicates with the main device 102of the keyphone system, performs the ISDN protocol, and provides theinterface between the main device 102 of the keyphone system and the BRIof the ISDN. The ROM 106 stores the function program and the referencedata for performance of the ISDN protocol. The RAM 108 temporarilystores the data in accordance with performance of the program of the CPU104. The dual port RAM 110 provides a path for communication with themain device 102, that is, the communication between the CPU 104 and thekeyphone system. The IDEC 112 used as the component for controlling fourD channels at the same time, can be for example, a PEB-2075 of theSIEMENS Ltd. company. The EPIC 114 used as the component for switching32 64 Kbps channels, for example, can be a PEB-2055 of the SIEMENS Ltd.company, and connects the channel of the main device 102 with the Bchannel of the BRI connected to the QUAT-S 116. The QUAT-S 116 used asfour BRI interface component, can be a PEB-2084 of the SIEMENS Ltd.company, and connects the BRI trunk 100 to the BRI as four wire ISDNphysical lines. The BRI trunk 100 performs all of protocols related tothe ISDN as mentioned previously and transceives the message necessaryfor performance of the ISDN protocol with the main device 102 of thekeyphone system through the dual port RAM 110.

[0026] In the BRI trunk 100, the software for performing the ISDNprotocol by the CPU 104 includes an initial entity 200, a layermanagement entity 202, an application entity 204, a call control entity206, a network signaling entity 208, a data link entity 210, and aphysical entity 212, as shown in FIG. 2. FIG. 2 is a block diagramshowing the construction of a software for performing the ISDN protocolin the BRI trunk of an ISDN keyphone system. Also, in FIG. 2, theprogram is divided by the software modules according to the nature ofthe job and each module is called an entity. The entities are performedby the CPU 104 and the arrows connecting entities comprise the messageflow between entities.

[0027] The initialization entity 200 among these entities is the modulewhich is firstly performed after resetting the BRI trunk 100 or power onresetting the keyphone system. The initialization entity 200 sets allkinds of initial values of the system and transmits the configurationstart message to perform the configuration for each layer, to the layermanagement entity 202.

[0028] The layer management entity 202 is the module for managing all ofthe entities, namely, the application entity 204, the call controlentity 206, the network signaling entity 208, the data link entity 210,and the physical entity 212. The layer management entity 202 performsthe configuration for each layer and manages the significant eventinfluenced by the other entities among the events generated at eachentity. As an example of the event, there is often generated line damageat the physical entity 212.

[0029] The application entity 204 is the module for transceiving themessage with the main device 102 of the keyphone system as shown inFIG. 1. The application entity 204 changes the message received from themain device 102 of the keyphone system into the message format processedby the call control entity 206, transmits the changed message, changesthe message received from the call control entity 206 into the messageformat processed by the main device 102 of the keyphone system andtransmits the changed message.

[0030] The call control entity 206 is the module for managing the calland interfacing with the application entity 204. The call control entity206 receives the message related to the performance of the user from theapplication entity 204, makes the message conform with thecurrently-selected ISDN protocol, and transmits the message to thenetwork signaling entity 208. When receiving the message from thenetwork signaling entity 208, the call control entity 206 checks whetheror not the received message conforms with the selected message, andtransmits the checked result to the application entity 204. When aresponse for transmitting the message to the network is required, thecall control entity 206 generates the response message and transmits thegenerated message to the network signaling entity 208.

[0031] The network signaling entity 208 is the module for performing theD channel signaling protocol. The network signaling entity 208 checkswhether or not the message received from the data link entity 210conforms with the selected message, and transmits the checked result tothe call control entity 206. The network signaling network 208 generatesthe message requiring the transmission from the call control entity 206to the network, in accordance with the currently-selected ISDN protocoland transmits the generated message to the data link entity 210.

[0032] The data link entity 210 is the module for performing an LAPD(link access procedure on D channel) protocol or an LAPB (link accessprocedure on B channel) protocol, and selects the LAPD or the LAPBdepending upon its configuration. The data link entity 210 receives themessage for transmission from the network signaling entity 208,generates the message in conformity with the format of thecurrently-selected ISDN protocol, and transmits the generated message tothe physical entity 212. The data link entity 210 checks whether or notthe message received from the physical entity 212 conforms with theselected ISDN protocol and transmits the checked result to the networksignaling entity 208.

[0033] The physical entity 212 is the module being directly connectedhardwarely to the ISDN physical line, and manages the deactivation andthe activation of the physical line. The physical entity 212 receivesthe message for transmission from the data link entity 210 and transmitsthe received message through the ISDN physical line to the HDLC(high-level data link control) frame. The physical entity 212 transmitsthe HDLC frames received from the ISDN physical line to the data linkentity 210.

[0034] In the BRI trunk as described above, the present invention cancommonly use the ISDN protocol for all countries or networks with onlyone BRI trunk. To meet it, the present invention previously stores thefunction program for supporting the ISDN protocol for the expectedcountry or network which will be used by the ISDN keyphone system, inthe ROM 106 of the BRI trunk 100. At this point, the present inventionbeforehand makes the list for the start addresses for each functionprogram as an all function list table and stores the all function listtable in the ROM 106. The function program stored in the ROM 106 isequal to the conventional function program for supporting thecorresponding ISDN protocol. Also, the present invention beforehandmakes the kind of countries and networks applicable to the ISDN protocolby the function program stored in the ROM 106, namely, the list of thecountry codes and the network codes form the country-network list tableand the table is stored in the ROM 106.

[0035] Herein, the program of the country-network list table will begiven hereinafter. construct network COUNTRY_NETWORK[]= {{EUROPE, ETSI},{FRANCE, FT_VN3}, {UK,   BT_ISDN2}, {GERMANY,DT_1TR6}, {SWEDEN,SWD_TVKT}, {BELGIUM, BG_V1),};

[0036] In this state, during the initial operation, the CPU 104 of theBRI trunk 100 performs the configuration operation according to theconfiguration message transceiving procedure of FIG. 3 according to anembodiment of the present invention, receives the information for thecountries and kinds of networks to be currently operated from the maindevice 102 of the keyphone system and forms the execution functiontable. In this instance, the main device 102 of the keyphone systemtransmits the information for the countries and kinds of networks to becurrently operated, to the BRI trunk 100. The execution function tableis comprised of the start address list of the function programcorresponding to the countries and the networks to be currently operatedby the function program belonging to the all function list table. Thecountries and kinds of networks to be currently operated means the kindof ISDN installed and connected currently to the ISDN keyphone system.Thereafter, the BRI trunk 110 can provide normal services by performingthe ISDN protocol according to the countries and kinds of networks to becurrently operated by the execution function program depending upon theexecution function table formed as stated above. Accordingly, even inthe case that the country and the network are varied by making theexecution function table with selecting the function program accordingto the countries and the networks to be currently operated, from the allconfiguration function list upon initialization, the present inventionhas no need to replace the ROM 106 of the BRI trunk 100 with a new ROM.

[0037] Now, the present invention will be more concretely explainedbelow with reference to FIGS. 3 to 10.

[0038]FIG. 3 is a diagram showing processes of transceiving theconfiguration message between software modules according to anembodiment of the present invention, which shows the kind and thetransmission direction of the message transmitted according to anembodiment of the present invention between the main device 102 of thekeyphone system and the entities as depicted in FIG. 2 performed in theCPU 104 of the BRI trunk 100 as illustrated in FIG. 1. The arrowsconnected between the entities indicate the transmission direction ofthe message, and reference numerals MSG1 to MSG16 at each arrow indicatemessage generation order. The procedure of processing the messagegeneration orders MSG1 to MSG16 is called a “configuration procedure”.Further, in following description, each message transmitted between theentities is for convenience of explanation, explained by referring tothe corresponding order of the message generation orders MSG1 to MSG16.Furthermore, the transmission of the message between the entities isperformed for itself by the CPU 104 and the transmission of the messagebetween the application entity 302 and the main device 102 of thekeyphone system is performed by the dual port RAM 110.

[0039] FIGS. 4A-4B and 9 are flowcharts showing processes for processingentities for performance of the configuration procedure according to anembodiment of the present invention, and FIG. 10 is a flowchart showingprocesses for processing the main device 102 of the keyphone systemaccording to an embodiment of the present invention. Herein, forconvenience, FIG. 4 is divided into FIGS. 4A and 4B and FIG. 5 isdivided into FIGS. 5A and 5B. Also, FIG. 4A is followed by FIG. 4B andFIG. 5A is followed by FIG. 5B.

[0040] Therefore, FIGS. 4A and 4B are flowcharts showing processes forprocessing the layer management entity according to an embodiment of thepresent invention, and FIGS. 5A and 5B are flowcharts showing processesfor processing the application entity according to an embodiment of thepresent invention.

[0041] When power is applied to the keyphone system or the BRI trunk 100is reset, the CPU 104 starts the configuration procedure from the layermanagement entity 300, that is, checks at step 400 of FIG. 4A whether ornot the configuration start message has been received from the maindevice 102 of the keyphone system. At this moment, the layer managemententity 300 starts the configuration procedure according to an embodimentof the present invention by receiving the configuration start message toperform the configuration for each layer from the initial entity 100 asshown in FIG. 2 where the initial values necessary for the system areset to general initialization. Firstly, when the configuration startmessage is received, the layer management entity 300 performs step 402.However, when other messages except for the configuration start messagehave been received at step 400, the layer management entity 300 performsa corresponding routine. Thus, at step 402, the layer management entity300 transmits the configuration request message MSG1 including theapplication configuration data to the application entity 302. Theapplication configuration data indicates ID(identification) representingthe specific countries and kinds of networks preset as the defaultvalue, that is, the country codes and the network codes. Also, theconfiguration request message MSG1 is the message requesting theapplication entity 302 to perform the configuration procedure. Afterthat, the layer management entity 300 at step 404 checks whether or notthe configuration checking message MSG6 has been received from theapplication entity 302.

[0042] The application entity 302 checks at step 500 of FIG. 5A whetheror not the configuration request message MSG1 has been received from thelayer management entity 300 and, when the configuration request messageMSG1 has been received therefrom, starts the configuration procedure atstep 502. When other messages except for the configuration requestmessage MSG1 have been received at step 500, the application entity 302performs the corresponding routine, conventionally. The applicationentity 302 receiving the configuration request message MSG1 at step 500,transmits the restart request message MSG2 to the main device 102 of thekeyphone system at step 502. The restart request message MSG2 is themessage requesting the main device 102 of the keyphone system to startthe new configuration procedure. Following that, the application entity302 checks at step 504, whether or not a parameter setting requestmessage MSG3 has been received from the main device 102 of the keyphonesystem.

[0043] Then, the main device 102 of the keyphone system starts theconfiguration procedure by receiving the restart request message MSG2from the application entity 302 of the BRI trunk 100 at step 1000 ofFIG. 10. At this time, when other messages except for the restartrequest message MSG2 have been received therefrom at step 1000, the maindevice 102 of the keyphone system performs the corresponding routine,conventionally. The main device 102 of the keyphone system whichreceives the restart request message MSG2 at step 1000, transmits theparameter setting request message MSG3 included in the parameter valuesas the country code and the network code set at the keyphone system bythe operator of the keyphone system, to the BRI trunk 100 at step 1002.The parameter setting request message MSG3 is the message which requeststhe BRI trunk 100 to set the parameters set at the keyphone system bythe operator. Hereinafter, the main device 102 of the keyphone systemchecks at step 1004, whether or not a parameter setting check messageMSG4 is received from the BRI trunk 100.

[0044] Upon the application entity 302 receiving the parameter settingrequest message MSG3 from the main device 102 of the keyphone system atstep 504, the application entity 302 checks whether or not the countrycode and the network code of the parameter values included in theparameter setting request message MSG3 exist in the country-network listtable stored in the ROM 106. At this point, when other messages exceptfor the parameter setting request message have been received at step504, the application entity 302 ignores the received message. Also, theapplication entity 302 transmits the parameter setting check messageMSG4 to the main device 102 of the keyphone system according to thechecked result at step 506, and at steps 508 and 510. When the countrycode and the network code of the parameter values included in theparameter setting request message MSG3 exist in the country-network listtable stored in the ROM 106, it means that the country code and thenetwork code have been correctly set by the operator. However, when thecountry code and the network code of the parameter values included inthe parameter setting request message MSG3 do not exist in thecountry-network list table stored at the ROM 106, it means that thecountry code and the network code have been incorrectly set.

[0045] Moreover, when the country code and the network code of theparameter values included in the parameter setting request message MSG3exist in the country-network list table, the application entity 302indicates the result value as being “OK”, includes the values in theparameter setting check message MSG4, and transmits it to the maindevice 102 of the keyphone system at step 510. The parameter settingcheck message MSG4 is the message for informing the checked result forthe parameter setting request, and “OK” indicates that the country codeand the network code set in the keyphone system by the operator arecorrectly set. When the country code and the network code of theparameter values included in the parameter setting request message MSG3do not exist in the country-network list table, the application entity302 indicates the result value as being “NOK”, includes all of thecountry codes and the network codes existing in the country-network listtable stored in the ROM 106, in the parameter setting check messageMSG4, and transmits it to the main device 102 of the keyphone system.The “NOK” indicates that the country code and the network code set inthe keyphone system by the operator are incorrectly set. When thecountry code and the network code of the parameter values included inthe parameter setting request message MSG3 do not exist at thecountry-network list table, it means that the codes have beenincorrectly set. Accordingly, the application entity 302 includes all ofthe country codes and the network codes in the parameter setting checkmessage MSG4 existing in the country-network list table so as to set themessage correctly and transmit it.

[0046] After that, upon the result value transmitted by being includedin the parameter setting check message MSG4 being “OK”, the applicationentity 302 checks at step 512, whether or not an initialization requestmessage MSG5 has been received from the main device 102 of the keyphonesystem. Unlike this, when the result value transmitted by being includedin the parameter setting check message MSG4 is “NOK”, the applicationentity 302 proceeds to step 504, thereby checking whether or not theparameter setting request message MSG3 has again been received from themain device 102 of the keyphone system.

[0047] When the main device 102 of the keyphone system receives theparameter setting check message MSG4 from the BRI trunk 100 in step 1004of FIG. 10, the main device 102 of the keyphone system checks at step1006 whether or not the result value included in the parameter settingcheck message MSG4 is “OK” at step 1006. At this event, once othermessages except for the parameter setting check message MSG4 have beenreceived in step 1004, the main device 102 of the keyphone systemignores the received message. However, when the result value included inthe parameter setting check message MSG4 is “NOK”, the main device 102of the keyphone system displays the country code and the network codeincluded in the content of the parameter setting check message MSG4 tobe seen by the operator and again sets the country code and the networkcode selected by the operator of the keyphone system at step 1008. Here,the operator of the keyphone system checks all of the country codes andthe network codes applicable at the BRI trunk 100, again selects andsets the right country code and the right network code. After settingthe country code and the network code, the main device 102 of thekeyphone system performs step 1002 once more. As a result, the maindevice 102 of the keyphone system again transmits the parameter settingrequest message MSG3 including the newly-set country code and networkcode to the BRI trunk 100 and the application entity 302 of the BRItrunk 100 again performs steps 504 to 506 in response to the transmittedmessage.

[0048] To the contrary, when the result value included in the parametersetting check message MSG4 is “OK” in step 1006, the main device 102 ofthe keyphone system transmit the initialization request message MSG5including the country code and the network code included in theparameter setting request message MSG3 to the BRI trunk 100 at step1010. The initialization request message MSG5 is for the messagerequesting initialization of the BRI trunk 100 so as to perform the ISDNprotocol corresponding to the country code and the network code includedin the parameter setting request message MSG3. Next, the main device 102of the keyphone system checks at step 1012 whether or not aninitialization check message MSG16 has been received from the BRI trunk100.

[0049] When the application entity 302 received the initializationrequest message MSG5 from the main device 102 of the keyphone system atstep 512, the application entity 302 performs step 514 of FIG. 5B. Inthis case, when other messages except for the initialization requestmessage MSG5 have been received at step 512, the application entity 302ignores the received message. Also, the application entity 302 changesthe country code and the network code of the application configurationdata into the country code and the network code included in theinitialization request message MSG5 and stores the changed message instep 514. Thereafter, the application entity 302 includes the changedcountry code and network code in the configuration check message MSG6with the application state value indicated as “OK” and transmits theincluded country code and network code to the layer management entity300 at step 516. The configuration check message MSG6 is the messagewhich informs the layer management entity 300 of the completion of theconfiguration procedure by the application entity 302. The transmissionof the application state value as “OK”, means that the configurationprocedure of the application entity 302 has been normally completed.Hereinafter, the application entity 302 checks at step 518 whether ornot an all configuration check message MSG15 has been received from thelayer management entity 300.

[0050] Upon the layer management entity 300 receiving the configurationcheck message MSG6 from the application entity 302 at step 404, thelayer management entity 302 stores the application state value includedin the configuration check message MSG6, and the country code and thenetwork code of the application configuration data at step 406. At thispoint, when other messages except for the configuration check messageMSG6 have been received, the layer management entity 300 ignores thereceived message. Hereinafter, the layer management entity 300 performssteps 408 to 430, thereby enabling the call control entity 304, thenetwork signaling entity 306, the data link entity 308, and the physicalentity 310 to perform the configuration procedure sequentially. At step408, the layer management entity 300 transmits the configuration requestmessage MSG7 including the country code and the network code of theapplication configuration data included in the configuration checkmessage MSG6 to the call control entity 304. The configuration requestmessage MSG7 requests the configuration procedure performance to thecall control entity 304. After that, the layer management entity 300checks at step 410 whether or not a configuration check message MSG8 hasbeen received from the call control entity 304.

[0051] Thus, the call control entity 304 starts the configurationprocedure from step 602 by receiving the configuration request messageMSG7 from the layer management entity 300 at step 600 of FIG. 6. In thisinstance, in the case that other messages except for the configurationrequest message MSG7 have been received in step 600, the call controlentity 304 performs the corresponding routine. However, at step 602, thecall control entity 304 which receives the configuration request messageMSG7, performs the configuration by forming the execution function tableusing the country code and the network code in the content of theconfiguration request message MSG7. At this case, the call controlentity 304 forms the country code and the network code included in theconfiguration request message MSG7 among the function programs existingin the all function list table stored in the ROM 106, that is, the startaddress list of the function program corresponding to the country andthe network to be currently operated, as the execution function table.In other words, the call control entity 304 selects the function programcorresponding to the country and the network to be currently operatedamong the function program stored at the ROM 106 and sets the executionfunction program. Accordingly, the call control entity 304 can performthe ISDN protocol according to the country and the network to becurrently operated by the function program depending upon the executionfunction table formed as stated above. After that, the call controlentity 304 sets the call control state value to “OK” and transmits theconfiguration check message MSG8 to the layer management entity 300, sothat the configuration procedure can be completed. Here, theconfiguration check message MSG8 is the message for informing the layermanagement entity 300 of the completion of the configuration procedure.Also, the transmission of the call control value as “OK” represents thatthe configuration procedure of the call control entity 304 has beencompleted.

[0052] When the layer management entity 300 receives the configurationcheck message MSG8 from the call control entity 304 at step 410, thelayer management entity 300 performs step 414 after storing the callcontrol state value included in the configuration check message MSG8 atstep 412. At this point, in the event that other messages except for theconfiguration check message MSG8 have been received therefrom, the layermanagement entity 302 ignores the received message. Thus, at step 414,the layer management entity 300 transmits the configuration requestmessage MSG9 including the country code and the network code of theapplication configuration data included in the configuration checkmessage MSG6 to the network signaling entity 306. The configurationrequest message MSG9 is the message requesting the configurationprocedure performance to the network signaling entity 306. Thereafter,the layer management entity 300 checks at step 416, whether or not theconfiguration check message MSG10 has been received from the networksignaling entity 306.

[0053] Then, the network signaling entity 306 starts the configurationprocedure from step 702 by receiving the configuration request messageMSG9 from the layer management entity 300 at step 700 of FIG. 7. In thisinstance, in the case that other messages except for the configurationrequest message MSG9 have been received at step 700, the networksignaling entity 306 performs the corresponding routine. However, atstep 702, the network signaling entity 304 receiving the configurationrequest message MSG9 in the above step 700, performs the configurationby forming the execution function table using the country code and thenetwork code in the content of the configuration request message MSG. Inthis case, the network signaling entity 306 forms the country code andthe network code included in the configuration request message MSG9among the function programs existing in the all function list tablestored in the ROM 106, that is, the start address list of the functionprogram corresponding to the country and the network to be currentlyoperated by the network signaling entity 306, as the execution functiontable. In other words, the network signaling entity 306 selects thefunction program corresponding to the country and the network to becurrently operated from among the function programs stored in the ROM106 and sets the execution function program. Accordingly, the networksignaling entity 306 can perform the ISDN protocol according to thecountry and the network to be currently operated by the function programdepending upon the execution function table formed as stated above.After that, at step 704, the network signaling entity 306 sets thenetwork signaling state value to “OK” and transmits the configurationcheck message MSG10 to the layer management entity 300, so that theconfiguration procedure can be completed. The configuration checkmessage MSG10 is the message for informing the layer management entity300 of the completion of the configuration procedure by the networksignaling entity 306. Also, the transmission of the network signaling“OK” value represents that the configuration procedure of the networksignaling entity 306 has been completed.

[0054] When the layer management entity 300 receives the configurationcheck message MSG10 from the network signaling entity 306, the layermanagement entity 300 performs step 420 after storing the networksignaling state value included in the configuration check message MSG10at step 418 of FIG. 4B. At this point, in the event that other messagesexcept for the configuration check message MSG10 have been receivedtherefrom, the layer management entity 300 ignores the received message.Thus, at step 420, the layer management entity 300 transmits theconfiguration request message MSG11 including the country code and thenetwork code of the application configuration data included in theconfiguration check message MSG6 to the data link entity 308. Theconfiguration request message MSG11 is the message requesting theconfiguration procedure performance to the data link entity 308.Thereafter, the layer management entity 300 checks at step 422, whetheror not the configuration check message MSG12 has been received from thedata link entity 308.

[0055] Then, the data link entity 308 starts the configuration procedurefrom step 802 by receiving the configuration request message MSG11 fromthe layer management entity 300 at step 800 of FIG. 8. In this instance,in the case that other messages except for the configuration requestmessage MSG11 have been received at step 800, the data link entity 308performs the corresponding routine. However, at step 802, the data linkentity 308 receiving the configuration request message MSG11 at step800, performs the configuration by forming the execution function tableusing the country code and the network code in the content of theconfiguration request message MSG11. In this case, the data link entity308 forms the country code and the network code included in theconfiguration request message MSG11 from among the function programsexisting in the all function list table stored in the ROM 106, that is,the start address list of the function program corresponding to thecountry and the network to be currently operated, as the executionfunction table. In other words, the data link entity 308 selects thefunction program corresponding to the country and the network to becurrently operated from among the function programs stored in the ROM106 and sets the execution function program. Accordingly, the data linkentity 308 can perform the ISDN protocol according to the country andthe network to be currently operated by the function program dependingupon the execution function table formed as stated above. After that, atstep 804, the network signaling entity 306 sets the data link statevalue to “OK” and transmits the configuration check message MSG12 to thelayer management entity 300, so that the configuration procedure can becompleted. The configuration check message MSG12 is the message forinforming the layer management entity 300 of the completion of theconfiguration procedure by the data link entity 308. Also, thetransmission of the data link value as “OK” represents that theconfiguration procedure of the data link entity 308 has been completed.

[0056] Upon the layer management entity 300 receiving the configurationcheck message MSG12 from the data link entity 308 at step 422, the layermanagement entity 300 performs step 426 after storing the data linkstate value included in the configuration check message MSG12 at step424. At this point, in the event that other messages except for theconfiguration check message MSG12 have been received therefrom, thelayer management entity 300 ignores the received message. Thus, at step426, the layer management entity 300 transmits the configuration requestmessage MSG13 including the country code and the network code of theapplication configuration data included in the configuration checkmessage MSG6, to the physical entity 310. The configuration requestmessage MSG13 is the message requesting the configuration procedureperformance to the physical entity 310. Thereafter, the layer managemententity 300 checks at step 428, whether or not the configuration checkmessage MSG14 has been received from the physical entity 310.

[0057] Then, the physical entity 310 starts the configuration procedurefrom step 902 by receiving the configuration request message MSG13 fromthe layer management entity 300 at step 900 of FIG. 9. In this instance,in the case that other messages except for the configuration requestmessage MSG13 have been received in step 900, the physical entity 310performs the corresponding routine. However, at step 902, the physicalentity 310 receiving the configuration request message MSG13 at step900, performs the configuration by forming the execution function tableusing the country code and the network code in the content of theconfiguration request message MSG13. In this case, the physical entity310 forms the country code and the network code included in theconfiguration request message MSG13 from among the function programsexisting in the all function list table stored in the ROM 106, that is,the start address list of the function program corresponding to thecountry and the network to be currently operated, as the executionfunction table. In other words, the physical entity 310 selects thefunction program corresponding to the country and the network to becurrently operated from among the function programs stored in the ROM106 and sets the execution function program. Accordingly, the physicalentity 310 can perform the ISDN protocol according to the country andthe network to be currently operated by the function program dependingupon the execution function table formed as stated above. After that, atstep 904, the physical entity 310 sets the data link state value to “OK”and transmits the configuration check message MSG14 to the layermanagement entity 300, so that the configuration procedure can becompleted. The configuration check message MSG14 is the message forinforming the layer management entity 300 of the completion of theconfiguration procedure by the physical entity 310. Also, thetransmission of the data link value as “OK” represents that theconfiguration procedure of the physical entity 310 has been completed.

[0058] Upon the layer management entity 300 receiving the configurationcheck message MSG14 from the physical entity 310 at step 428, the layermanagement entity 300 performs step 432 after storing the physical statevalue included in the configuration check message MSG14 at step 430. Atthis point, in the event that other messages except for theconfiguration check message MSG14 have been received therefrom, thelayer management entity 300 ignores the received message. Thus, at theabove step 432, the layer management entity 300 ends the configurationprocedure by transmitting the all configuration check message MSG15having the configuration state of all entities, that is, the informationsuch as the application state value, the call control state value, thenetwork signaling state value, the data fink state value, and thephysical state value, to the application entity 302. The allconfiguration check message MSG15 is the message informing thecompletion of the configuration state of all entities.

[0059] Once the application entity 302 receives the all configurationcheck message MSG15 at step 518, the application entity 302 completesthe configuration procedure by transmitting the initialization checkmessage MSG16 having the configuration state of all entities included inthe all configuration check message MSG15, to the main device 102 of thekeyphone system at step 520. At this time, when other messages exceptfor the all configuration check message MSG15 have been received, theapplication entity 302 ignores the received message. The initializationcheck message MSG16 represents the completion of the configurationoperation in order to perform the ISDN protocol for the country and thenetwork to be currently operated by the BRI trunk 100, that is, toperform all of entities for the ISDN protocol.

[0060] When all configuration procedure of the BRI trunk 100 iscompleted by the above operation, the BRI trunk 100 performs the normaloperation. That is, the BRI trunk 100 can provides normal service byperforming the ISDN protocol according to the country and the network tobe currently operated by the function program as the execution functiontable formed by the configuration procedure as stated above.

[0061] Meanwhile, upon the main device 102 of the keyphone systemreceiving the initialization check message MSG16 at step 1012, the maindevice 102 of the keyphone system completes the configuration procedureafter storing the country code and the network code set by the operatorat step 1014. Namely, the main device 102 of the keyphone system storesthe country code and the network code as the currently-operated countrycode and network code with the above configuration order. Here, whenother messages except for the initialization check message MSG16 havebeen received, the main device 102 of the keyphone system ignores thereceived message.

[0062] Accordingly, it is unnecessary to replace the ROM 106 of the BRItrunk 100 with a new ROM even when the country and the network arevaried by making the execution function table with selecting thefunction program according to the country and the network to becurrently operated, from the all configuration function list table. Thatis to say, one BRI trunk 100 can be commonly used in all countries andnetworks which have protocols different from one another.

[0063] As apparent form the foregoing, the present invention has no needto replace the ROM storing the program for performance of the ISDNprotocol with the new ROM whenever the country and the network arevaried by commonly using one BRI trunk for all countries and networkswhich have ISDN protocols different from one another.

[0064] While there has been illustrated and described what areconsidered to be preferred embodiments of the present invention, it willbe understood be those skilled in the art that various changes andmodifications may be made, and equivalents may be substituted forelements thereof without departing from the true scope of the presentinvention. In addition, many modifications may be made to adapt aparticular situation to the teaching of the present invention withoutdeparting from the central scope thereof. Therefore, it is intended thatthe present invention not be limited to the particular embodimentsdisclosed as the best modes contemplated for carrying out the presentinvention, but that the present invention includes all embodimentsfalling within the scope of the appended claims.

What is claimed is:
 1. A method for configuring a network interfacecircuit in an integrated services digital network keyphone system,comprising the steps of: first storing in a read only memory (ROM) ofthe network interface circuit all function programs supporting anintegrated services digital network protocol for each country andnetwork which will be used by the keyphone system; selecting a functionprogram corresponding to the country and kind of network to be operatedupon initialization from among the function programs stored in the ROM;and setting the selected program, as an execution function program. 2.The method as defined in claim 1, said initialization being executedwhen said keyphone system is power on reset and said network interfacecircuit is reset.
 3. The method as defined in claim 2, said integratedservices digital network protocol being performed according to saidexecution function program upon normal operation of said system.
 4. Amethod for configuring a network interface circuit in an integratedservices digital network keyphone system, comprising the steps of: firststoring in a read only memory (ROM) of the network interface circuit allfunction programs supporting an integrated services digital networkprotocol for each country and network which will be used by the keyphonesystem; receiving a country code and a network code to be currentlyoperated from a main device of said keyphone system upon initialization;and selecting a function program corresponding to said country code andnetwork code from among the function programs stored in said ROM andsetting the selected program as an execution function program.
 5. Themethod as defined in claim 4, said initialization being executed whensaid keyphone system is power on reset and said network interfacecircuit is reset.
 6. The method as defined in claim 5, said country codeand said network code being set in correspondence with the countries andkinds of networks to be currently operated by an operator of saidkeyphone system.
 7. The method as defined in claim 6, furthercomprising: executing said integrated services digital network protocolin accordance with said execution function program upon normal operationof said system after completion of configuration.
 8. The method asdefined in claim 7, all of the country codes and network codescorresponding to the function programs stored in said ROM beingtransmitted to said main device and are again set, upon said countrycode and said network code not being supported by the function programstored in said ROM.
 9. A method for configuring a network interfacecircuit in an integrated services digital network keyphone system,comprising the steps of: (a) first storing in a read only memory (ROM)of the network interface all function programs of supporting anintegrated services digital network protocol for each country andnetwork which will be used by said keyphone system, receiving a countrycode and a network code to be currently operated from a main device ofsaid keyphone system through an application entity by a layer managemententity upon initialization; and (b) selecting a function programcorresponding to said country code and network code from among thefunction programs stored in said ROM by a call control entity, a networksignaling entity, a data link entity, and a physical entity, and settingthe selected program as an execution function program.
 10. The method asdefined in claim 9, step (b) being comprised of: (c) requesting saidcall control entity, said network signaling entity, said data linkentity, and said physical entity to perform a configuration for saidcountry code and network code by said layer management entity,sequentially; (d) selecting a function program for said country code andnetwork code according to a configuration need from said layermanagement entity by said call control entity, said network signalingentity, said data link entity, and said physical entity, from among thefunction programs stored in said ROM and setting the selected program asthe execution function program; and (e) informing the configurationcompletion by said layer management entity through said applicationentity to said main device after completing the configuration of saidcall control entity, said network signaling entity, said data linkentity, and said physical entity.
 11. The method as defined in claim 10,said step (d) being executed by forming a start address list of saidexecution function programs as an execution table.
 12. The method asdefined in claim 11, said initialization being executed when saidkeyphone system is power on reset and said network interface circuit isreset.
 13. The method as defined in claim 12, said country code and saidnetwork code being set in correspondence with the countries and kind ofnetworks to be currently operated by an operator of said keyphonesystem.
 14. The method as defined in claim 13, farther comprising:executing said integrated services digital network protocol inaccordance with said execution function program upon normal operation ofthe system after completion of configuration.
 15. The method as definedin claim 14, further comprising: upon said country code and said networkcode not being supported by the function program stored in said ROM,transmitting all of the country codes and network codes corresponding tothe function programs stored in said ROM to said main device by saidlayer management entity; and displaying all of the country codes andnetwork codes received from said layer management entity by said maindevice and transmitting a country code and network code set again bysaid operator, to said layer management entity.